/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_scale_q15.c
*
* Description:	Multiplies a Q15 vector by a scalar.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated
*
* Version 0.0.7  2010/06/10
*    Misra-C changes done
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup scale
 * @{
 */

/**
 * @brief Multiplies a Q15 vector by a scalar.
 * @param[in]       *pSrc points to the input vector
 * @param[in]       scaleFract fractional portion of the scale value
 * @param[in]       shift number of bits to shift the result by
 * @param[out]      *pDst points to the output vector
 * @param[in]       blockSize number of samples in the vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.15 format.
 * These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.
 */


void arm_scale_q15(
    q15_t* pSrc,
    q15_t scaleFract,
    int8_t shift,
    q15_t* pDst,
    uint32_t blockSize)
{
	int8_t kShift = 15 - shift;                    /* shift to apply after scaling */
	uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */
	q15_t in1, in2, in3, in4;
	q31_t inA1, inA2;                              /* Temporary variables */
	q31_t out1, out2, out3, out4;


	/*loop Unrolling */
	blkCnt = blockSize >> 2u;

	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* Reading 2 inputs from memory */
		inA1 = *__SIMD32(pSrc)++;
		inA2 = *__SIMD32(pSrc)++;

		/* C = A * scale */
		/* Scale the inputs and then store the 2 results in the destination buffer
		 * in single cycle by packing the outputs */
		out1 = (q31_t)((q15_t)(inA1 >> 16) * scaleFract);
		out2 = (q31_t)((q15_t) inA1 * scaleFract);
		out3 = (q31_t)((q15_t)(inA2 >> 16) * scaleFract);
		out4 = (q31_t)((q15_t) inA2 * scaleFract);

		/* apply shifting */
		out1 = out1 >> kShift;
		out2 = out2 >> kShift;
		out3 = out3 >> kShift;
		out4 = out4 >> kShift;

		/* saturate the output */
		in1 = (q15_t)(__SSAT(out1, 16));
		in2 = (q15_t)(__SSAT(out2, 16));
		in3 = (q15_t)(__SSAT(out3, 16));
		in4 = (q15_t)(__SSAT(out4, 16));

		/* store the result to destination */
		*__SIMD32(pDst)++ = __PKHBT(in2, in1, 16);
		*__SIMD32(pDst)++ = __PKHBT(in4, in3, 16);

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4u;

	while(blkCnt > 0u) {
		/* C = A * scale */
		/* Scale the input and then store the result in the destination buffer. */
		*pDst++ = (q15_t)(__SSAT(((*pSrc++) * scaleFract) >> kShift, 16));

		/* Decrement the loop counter */
		blkCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

	while(blkCnt > 0u) {
		/* C = A * scale */
		/* Scale the input and then store the result in the destination buffer. */
		*pDst++ = (q15_t)(__SSAT(((q31_t) * pSrc++ * scaleFract) >> kShift, 16));

		/* Decrement the loop counter */
		blkCnt--;
	}

#endif /* #ifndef ARM_MATH_CM0 */

}

/**
 * @} end of scale group
 */
